Brand: F-250's check engine light keeps coming on

Q: My 2003 Ford F250 6-liter turbo diesel with 57,000 “babied” miles is a costly concern. For three years, the “check engine” light comes on while driving. Two-thousand miles back, the Ford dealer replaced the turbo (rebuilt) and EGR valve at a cost of $3,000. Recently I took it back for the engine light and was told that I need a new turbo and EGR valve. I was informed that the turbo was not performing to its peak as the variable vanes were possibly corroded due to lack of use. Frankly, it seems to be running fine, even though the engine light is on.

A: Did the dealer offer any help with the cost of replacing the turbo and EGR valve after just 2,000 miles? More to the point, in order to identify the problem, it is important to record the DTC fault codes that triggered the check engine light. Without the specific fault codes, we can only guess at the issue.

My ALLDATA automotive database pulled up TSB 09-16-5, dated August 2009, that addresses low performance/turbo issues. It describes the possibility of “coking” in the turbocharger. This can occur when oil that lubricates the turbo bearings bakes or “cokes” from residual heat after shutting down the engine. Over time these deposits can build up to the point of impeding the response of the variable vanes in the turbo, causing high or low exhaust pressure leading to under or overboost and inaccurate EGR function.

It seems unlikely that the vanes have corroded in just 2,000 miles, but the coking deposits may well be causing the issue. Ask the Ford dealer three things — the precise DTC fault codes downloaded, whether cleaning the vanes in your turbo would help, and finally, will they pay part or all of the cost of replacing a 2,000-mile-old turbo?

Q: I live in Florida by the ocean and I took my 2007 Nissan 350Z to the dealership recently to have my oil changed. I received the invoice and checkup paper, which said the air filter needs replacing in the near future. What the heck does that mean? Shouldn’t they have asked me and done it when I was there? And also, how long before I should have it changed out?

A: The answer to each of your questions can be found in the owner’s manual for your vehicle. On my radio shows, I used to ask callers if they’d found the 10 dollar bill every carmaker leaves in the pages of the owner’s manual. The “what?’ response confirmed that they’d never read the manual. Good fun!

In this case, I think the dealer was being a “good guy” by reminding you of an upcoming scheduled maintenance item, specifically air cleaner replacement. Nissan recommends replacement at 30,000-mile intervals. Might your Z be approaching 30,000, 60,000 or 90,000 miles?

Q: I have a 2009 Chevy Malibu LT. Since May my interior lights have been going on and off sporadically. When I go over bumps, they flicker. In the morning on my way to work, they are completely off. Then around lunchtime when it’s hot, they are on — all day and night until I park it in a cool location. When it’s 65 degrees or less outside, the lights are off. I feel like it’s heat-induced, but am not sure how to fix the problem.

A: Since the illuminated entry system controlled by the body control module (BCM) turns on the interior lights when a door switch is activated, I’d focus on the door switches. When they close, the circuit in the BCM is grounded and the lights illuminate. Perhaps heat is expanding an involved component just enough to electrically trigger the switch. Check that the dimmer switch is not rotated to the point of turning on the lights and you could try switching the dome light to the “off” position. The BCM should turn off the courtesy lights after 20 minutes.